HealthDay News -- Every day in the United States, three children drown. Although many people expect a drowning child to splash and yell for help, these accidents often happen quietly without anyone noticing, according to a pediatric safety expert.

However, with proper training and supervision, drownings and other injuries are avoidable, said David Schwebel, director of the University of Alabama at Birmingham Youth Safety Lab.

"Backyard swimming pool drownings are far too common. These incidents are devastating to families, and they can be prevented," said Schwebel in a university news release. "A large portion of drownings actually occur quietly with little or no yelling or splashing. Many people drown while underwater and sink to the bottom, and only an observant lifeguard, parent or fellow swimmer can save that life."

The first step to take to protect children from drowning is to teach them to swim, Schwebel advised. "Swimming lessons are vital," he said. "The most recent scientific evidence suggests they may actually help a lot in reducing the risk of a child drowning while swimming."

Although learning how to swim is essential, even great swimmers can drown. Schwebel warned that all children, regardless of their swimming ability, must be constantly monitored while in water.

"Supervision is the first priority and not just intermittent checking," Schwebel cautioned. "A good supervisor must act like a lifeguard, constant and alert, not distracted by yard work, reading a magazine or text-messaging on a phone."

Among the other ways to keep children safe in the pool:

Keep count. Anyone supervising children in water should know how many swimmers are in the pool. They should keep a constant head count to ensure that all swimmers are accounted for and safe.

Enforce rules. Backyard pools need rules just like lifeguarded pools. Children should be expected to learn the rules and follow them to ensure their safety.

Swimming in the ocean is more dangerous and carries different risks than swimming in pools, Schwebel pointed out. Ocean currents can be unpredictable. Jellyfish and other ocean life can also cause injury, he added.

"If warnings are posted by lifeguards or other local authorities, they should be heeded," Schwebel advised. "You should never enter ocean water if authorities warn you that it's dangerous."

When swimming at a lake on in a river, it's never a good idea to jump in without knowing the depth of the water. Schwebel also cautioned that hidden rocks and logs could lie close to the surface of the water. Swimmers can hit these objects when jumping into the water.

"Swimming is great exercise, it is fun, and it keeps us cool in the hot summer," Schwebel concluded. "Children should learn to swim and learn to enjoy swimming, but we must always be alert of the risks of swimming and prevent drowning."